Reverted generic x86 linux config for Qt5.5. Fedora21 has specific Qt5.6...

Reverted generic x86 linux config for Qt5.5. Fedora21 has specific Qt5.6 config file. Eventually, the generic x86 linux config file will be updated for Qt5.6.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/branches/v006LibrariesV2@6725 41f8697f-d340-4b68-9986-7bafba869bb8